Value of magnetic resonance imaging for muscle denervation syndromes of the shoulder girdle

Clinical evaluation of neuromuscular disorders typically consists of obtaining a detailed clinical history, physical examination, and electrophysiologic examinations. Electrodiagnostic examinations significantly aid in distinguishing between myopathy, neuropathy, and neuromuscular disorders. Electrodiagnostic examinations also assist in determining the severity and extent of disease. Progress can also be monitored on follow-up testing. The benefit of magnetic resonance imaging (MRI) in neuromuscular disease evaluation lies primarily in identifying a specific underlying gross pathologic cause and its location in the neuraxis as well as in identifying associated secondary findings. In some cases, MRI is particularly helpful when a solitary, small, deep muscle is affected. Imaging can be useful in assessing clinical progress in some cases. Causes of muscle denervation include mass lesions and trauma as well as infectious, autoimmune, and idiopathic causes. This article illustrates the common denervation syndromes that involve the shoulder girdle: Parsonage-Turner syndrome, quadrilateral space syndrome, and suprascapular neuropathy. By demonstrating the exact muscles involved and spared, MRI non-invasively identifies the level of nerve insult in the neuraxis. Furthermore, in cases in which a mass is responsible for denervation, MRI can directly show the cause and aid in treatment planning.